Biomedical subjects
Publications and source records attributed to R van Heyningen.
BACKGROUND: It has been suggested that season of birth might influence the susceptibility to cataract in later life. METHODS: This hypothesis was investigated using data pooled from two case-control studies carried out in Oxfordshire. RESULTS/CONCLUSION: The results showed no relation between month or season of birth and cataract in later life in an English population.
Data from two case control studies in Oxfordshire were combined and analysed. The combined study covered 1940 subjects, 723 cases, and 1217 controls, between the ages of 50 and 79 with a response rate of 97% for cases and 94% for controls. Diabetes was shown to be a powerful and highly significant risk factor for cataract with a relative risk of 5.04. More than 11% of cataracts in Oxfordshire are attributable to diabetes. The relative risk did not increase significantly with age within the range 50 to 79 years but was higher in females than in males. For females with diabetes the relative risk was 7.85 with 95% confidence interval from 4.30 to 14.3 compared with 3.42 with confidence interval from 2.05 to 5.71 for males with diabetes. Diabetes remained a powerful risk factor when other identified risk factors had been controlled for. No known mechanism for the development of diabetic complications provides an explanation for the excess risk in females. Combination of the two studies led to better estimates of the relative risk of glaucoma as a risk factor for cataract (3.96 with 95% confidence interval from 2.35 to 6.68). The relative risk appeared to be greater in women than in men but this difference was not statistically significant. There was no significant change in risk with age. Glaucoma is a powerful and independent risk factor for cataract in both sexes and may be responsible for 5% of all cataracts in our area.
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Three hundred patients with cataract and 609 control subjects with the same age-sex distribution were interviewed in a study of cataract in Oxfordshire, England. The risks associated with severe diarrhoea, glaucoma, and work on a military base have been demonstrated. Population attributable risks were calculated for those and other risk factors.
A case-control study of cataract in Oxfordshire explored the risks and benefits associated with a variety of drugs. Steroids including the diuretic spironolactone, nifedipine, heavy smoking, and beer drinking were associated with a raised risk. On the other hand aspirin-like analgesics (paracetamol, ibuprofen, aspirin, etc. appeared to protect against cataract. Cyclopenthiazide appeared to provide a similar protection.
Cataract is the major cause of blindness worldwide. It is a greater problem in third world countries than in the West and several attempts have been made to explain the excess in these countries. This paper provides an overview of the literature especially on studies designed to identify risk factors for cataract. There is an association between poverty and cataract and, more specifically, between cataract and a history of severe diarrhoea-dehydration. Recent results from a case-control-led study of cataract in Oxford are also presented with the quantitation of risks associated with a number of factors including diarrhoea, renal failure and diabetes. In this study an apparently protective effect of aspirin, paracetamol and similar drugs was observed. This protective effect applies to the risk associated with diabetes.
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The results of a case-control study of 300 cataract patients and 609 controls indicate that long-term use of aspirin-like analgesics halves the risk of cataract. Myopia and the use of nifedipine were found to carry a significant risk of cataract, and renal failure appeared to carry a high risk, though few patients were affected. The results also confirm diabetes, glaucoma, and use of steroids as risk factors for cataract.
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14C palmitic acid is oxidized in vitro by the intact human, monkey, bovine, rabbit, and rat lens. 14CO2 and 14C-glutamic acid are formed.
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I have discussed five aspects of lens metabolism and their possible relationship to cataract in man, and this has left me with five fundamental questions to be answered. 1. Are the fluorescent tryptophan derivatives, found only in the lens of man and higher primates, involved in the development of brown nuclear cataract? 2. Is naphthalene cataract in rabbits a model for any type of cataract in man--i.e., are quinones ever formed in the human eye? 3. Is diabetes the only cataract in which osmotic swelling is important? 4. Does self-digestion of protein in the human lens contribute to cataract development? 5. Are the consequences of the abnormal maturation of lens fibers, which occurs in tryptophan deficiency cataract in rats, ever seen in man?